This won't be one table. Depends upon your type of "production order". I would start with coois transaction. If you need to look at tables JEST, AFRU, AFPO, AFKO would be a start. JEST is the table that gives you status of order. Status of REL and not DLV, not TECO.

Fakir --
You probably should not jump into a customized report without first thoroughly exploring the capabilities of the COOIS transaction (if you are using process orders, then use COOISPI).
The system status selections may be sufficient to identify WIP, but you'll probably need a Status Selection Profile. SAP installs with a number of "canned" profiles, but we ended up using a couple of custom profiles because we wanted to include user status conditions in our search. Status profiles are pretty easy to configure using transaction BS02.
Once you have a status profile that identifies your definition of WIP, then you can create COOIS variants so it's easy for different users to focus on the orders they are most interested in. You can create standard layouts, too.
Even if you do not provide "perfect" visibility to your users using COOIS, by the time you've set up meaningful search criteria and layouts you and your users will have a much better understanding of exactly what kind of WIP visibility they really need.
[Side note on the Technical Completion and Close dates on the order header, AUFK-IDAT2 and IDAT3. These dates are set the first time you set the TECO or CLSD on the order. If you "undo" the status, these dates remain as they were. We do not use these dates in our custom visibility because we have legitimate reasons for unTECOing orders and then reTECOing them and the date we want is the most recent TECO date.]
Good luck,
Carl